The invention concerns a device for handling individual sheets to and from a stack, particularly, film sheets for x-ray devices, in which each individual sheet of the stack is transferred between a lateral plane defining the top of the stack and sheet transport roller means.
A known problem in existing film exchanges, particularly in connection with x-ray installations, is the separation of individual sheets of flat film stacked in a feeder magazine in such a manner that only one sheet is transported to the exposure station of the film exchanger. Delivery of a plurality of sheets simultaneously would make an exposure impossible.
One known type of feeder magazine utilizes a sheet drive or transport means in which an upper drive roller forms a nip with a lower running lower so that the sheet conveyed to the drive roller is seized between the drive and running rollers, enabling the drive roller to pass the sheet to or from a storage housing. The running roller is intermittently swiveled into the plane of the drive roller to form the transport nip. A disadvantage of this known arrangement occurs in the rapid transporting of film sheets since when the running roller is pivoted against the drive roller it can rebound and continuity of film transport may be disrupted. Under certain circumstances, the rebound effect on the running roller can result in several film sheets being transported together. In addition, when the running roller strikes the drive roller, vibrations arise in the film exchanger device which can ultimately lead to disturbances in sensitive components, as well as possibly disrupt picture quality in the film exchanger connected to the transport device.
The present invention calls for film transport means for use in a film sheet storage mechanism that can assure the transport of individual sheets one at a time regardless of the transport velocity and avoids detrimental vibrations resulting in the drive roller.